In Vitro Plantlet Regeneration and Accumulation of Phenolic Compounds in Microshoots of Astragalus glycyphyllos L.

Astragalus glycyphyllos (Fabaceae) is known to be a source of flavones, flavonols, and isoflavones, and its in vitro culture may promote the efficiency and sustainability of obtaining pharmacologically valuable fractions. The aim of this study was to develop an effective plantlet regeneration protocol for A. glycyphyllos, providing the accumulation of phenolic compounds and antioxidants in cultured tissues. The results show a maximum seed germination rate (67.8%) after scarification (mechanical with sandpaper followed by treatment with 50% sulfuric acid) and subsequent sterilization with 1.1% sodium hypochlorite solution. The maximum regeneration rate (95%) was achieved on Murashige and Skoog medium supplemented with 0.5 mg·L−1 thidiazuron. A thidiazuron concentration of 0.05 mg·L−1, combined with a twofold increase in iron chelate content, induced the maximum yield of total flavonoids (8.74 mg·g−1 DW), and significant levels of total phenolics (4.15 mg·g−1) and antioxidants (1.83 mg AAE·g−1) in the microshoot tissues. HPLC analysis showed kaempferol glycosides (1.51 mg·g−1) and acylated kaempferol glycosides (2.76 mg·g−1) as major components. Formononetin in a modest amount (0.09 mg·g−1) was detected in hydrolyzed extracts. The phenolic profiles of the microshoots and native plants coincided in hydroxycinnamic acid composition; meanwhile, quercetin glycosides were present only in in situ plants, and formononetin was found only in the plantlets. The results confirm the prospects of biotechnological methods for the industrial production of standardized medicinal raw materials.